Epidemiology of Frailty in Older People.

Frailty is a complex of symptoms that is characterized by impaired stress tolerance due to a decline in the functionality of different organs. Due to its multifactorial aetiology, several definitions and assessments of this symptom complex have been developed, of which the Fried Frailty Score (Phenotype Score) and the broader Frailty Index (Deficit Accumulation Index) are the most commonly used. The prevalence of frailty increases with age independently of the assessment instrument and ranges between 4 and 59% in community-dwelling elderly populations and is higher in women than in men. The actual prevalence rate in a population depends on the prevalence of chronic diseases including depression, nutritional status, and inherently socio-economic background and education. Frailty is, however, not a steady state and progression, but also reversion is common. Although numerous studies on the prevalence of frailty have been conducted, systematic assessments in different populations are rare, which reduces the comparability of results. Similarly heterogeneous, but less frequent are studies on the incidence and on trajectories and transitions of frailty, calling for further, more systematic studies on this topic.